Lifting weights helps adults gain muscle — studies show it consistently leads to modest muscle growth when done regularly.

If healthy guys between 18 and 40 lift weights regularly for at least two weeks up to a year, they typically gain about 1.5 kilograms of muscle—no matter what kind of weight routine they follow.

When you lift weights over time, the main reason your body becomes leaner and more muscular is because your muscles grow bigger—not because you're losing fat or anything else.

Untrained individuals undergoing resistance training with a significant caloric surplus achieve high rates of muscle hypertrophy with relatively low concomitant fat accumulation.

Most of the research on how much to lift and how often was done on young men who already train—so we don’t know if the same rules apply to women, older people, or beginners.

In individuals with elevated body fat stores, resistance training during a caloric deficit can sustain muscle hypertrophy while promoting net fat loss.